Simon Cowell, Justin Bieber, Ashton Kutcher and Miley Cyrus are all victims of the hoax known as 'swatting.' No one's been arrested, and laws haven't caught up.

The distress call came Sunday around 1 p.m.: emergency in Beverly Hills. Someone was being held hostage at "Simon Cowell's." The victim, reported a female caller, was tied up with duct tape inside a bathroom at the brash British "X Factor" judge's hillside mansion.

A similar call reached the Los Angeles County Sheriff's Department on Oct. 10 before 2 a.m. Someone inside a gated Calabasas mansion reported shots fired and said the gunman was threatening residents, making clear he'd put police in his cross hairs when they showed up.

Unbeknown to sheriff's deputies, that mansion belonged to the most famous teenager on the planet, Justin Bieber. Multiple squad cars were scrambled and heavily armed deputies arrived. They swept Bieber's residence and two others on the street before discovering it was all a hoax. The pop star, on tour at the time, was nowhere near the mansion.

Cowell was home when Beverly Hills police arrived at his residence. But there was no hostage negotiation, no armed standoff, nor were any arrests made. "The dispatcher believed the call was a hoax," said Lt. Lincoln Hoshino of the Beverly Hills Police Department.

Count Bieber and Cowell as the latest high-profile victims of "swatting," a fast-growing phenomenon masterminded by anonymous mischief-makers who alert police to a bogus crime situation, prompting a tactical response — sometimes by SWAT officers — that involves a high-risk search for phantom assailants. Several officers have already been injured responding to such calls, and officials, including Los Angeles Police Chief Charlie Beck, fear that it's only a matter of time before events turn deadly.

Within Hollywood, in an era when breaches of celebrity privacy have never been more invasive — by paparazzi, hacker journalists or even websites that provide detailed information about stars' homes and street addresses — the pranks have taken on troubling dimensions.

"Swatting is a very real problem for those in the public eye," said Blair Berk, a criminal lawyer who has represented stars including Mel Gibson, Kanye West and Lindsay Lohan. "It is only a matter of time before someone dies because of this stupidity."

What started a decade ago as a malicious prank among computer gamers is quickly evolving into a Grade-A crisis for law enforcement nationwide, encouraging new legislation aimed at stiffer punishments for swatters as well as redoubled attempts to defeat the "spoofing" technology that enables such cyber-troublemaking.

Chief Beck acknowledged that swatting has stretched the LAPD's emergency response capacity while also endangering victims by placing them in potential confrontation with police firepower.

"It not only draws public safety resources away from real emergencies, it places people at significant risk by the dispatch of armed police officers," said Beck. "Our big fear is that [swatting] will become more prevalent."

Hard to track

Chief Bill McSweeney of the Los Angeles Sheriff's Department says that the most sophisticated swatting maneuvers involve tricking caller ID so that a 911 call can be registered as having been placed from inside the very household being swatted.

Investigators say a 911 call reporting an armed home invasion that sent firefighters plus a dozen police officers swarming down on Miley Cyrus' unoccupied Studio City home in August may have originated from a cellphone, then bounced over several Internet providers to hide its origin. Bieber's swatting was called in through a device that allows hearing-impaired callers to send messages over the phone.

That kind of "spoofing" technology — an elaborate computer fake-out that falsifies data, obscures a person's digital identity and location and can even make a man's voice sound female — is legal and widely available on the Web.

"Any time you use a telephone or a computer, there is an electronic trail," said Philip Lieberman, founder and president of Lieberman Software, which specializes in computer security. Phone carriers and Internet providers monetize every digital communication and have a vested interest in tracking caller origination. "It is virtually impossible not to get caught unless they have a heavy level of sophistication."

But even with the advanced software used by the LAPD, tracing spoofed calls or teletexts can be difficult. "If these calls originate with a throwaway phone," McSweeney said, "sometimes those are hard to track."